CVE-2026-0421

// CVE-2026-0421 PoC Concept - BIOS Secure Boot Bypass // Note: This is a conceptual proof of concept for educational purposes only // Actual exploitation requires physical access and specialized firmware tools /* #include <stdio.h> #include <stdlib.h> #include <stdint.h> // Conceptual representation of Secure Boot bypass int check_secure_boot_status() { // Read Secure Boot configuration from BIOS uint32_t secure_boot_flag = read_bios_register(0x1234); // Normal check - should return 1 if Secure Boot is enabled if (secure_boot_flag & SECURE_BOOT_ENABLED) { return 1; // Secure Boot is ON } return 0; // Secure Boot is OFF } // Vulnerable implementation int vulnerable_secure_boot_check() { uint32_t sb_config = read_bios_nvram(SB_CONFIG_OFFSET); // The vulnerability exists here: // Attack can manipulate sb_config before this check // Even if BIOS shows "On", the actual check can be bypassed if (sb_config & USER_MODE_FLAG) { // Only affects User Mode - this is the vulnerable path // An attacker can modify this logic to disable SB return bypass_secure_boot(sb_config); // VULNERABLE } return SECURE_BOOT_ENFORCED; } // Mitigation: Verify Secure Boot state through multiple mechanisms void verify_secure_boot_integrity() { uint32_t primary_check = read_bios_register(PRIMARY_SB_FLAG); uint32_t secondary_check = read_uefi_variable(SB_VAR_NAME); uint32_t hardware_check = read_platform_register(HW_SB_FLAG); // All checks must be consistent if (primary_check != secondary_check || secondary_check != hardware_check) { // Inconsistency detected - potential attack trigger_security_alert(); halt_system(); } } */ # Python script to check Secure Boot status (for verification only) def check_secure_boot_status(): """ Check Secure Boot status via Windows PowerShell Note: This is for status verification, not exploitation """ import subprocess try: result = subprocess.run( ['powershell', '-Command', 'Confirm-SecureBootUEFI'], capture_output=True, text=True ) if result.returncode == 0: return "Secure Boot is ENABLED" else: return "Secure Boot is DISABLED or not supported" except Exception as e: return f"Error checking Secure Boot: {e}"

{"cve": {"id": "CVE-2026-0421", "sourceIdentifier": "[email protected]", "published": "2026-01-14T23:15:56.397", "lastModified": "2026-04-15T00:35:42.020", "vulnStatus": "Deferred", "cveTags": [], "descriptions": [{"lang": "en", "value": "A potential vulnerability was reported in the BIOS of L13 Gen 6, L13 Gen 6 2-in-1, L14 Gen 6, and L16 Gen 2 ThinkPads which could result in Secure Boot being disabled even when configured as “On” in the BIOS setup menu. This issue only affects systems where Secure Boot is set to User Mode."}, {"lang": "es", "value": "Una posible vulnerabilidad fue reportada en la BIOS de los ThinkPads L13 Gen 6, L13 Gen 6 2-en-1, L14 Gen 6 y L16 Gen 2, lo que podría resultar en que Secure Boot se desactive incluso cuando está configurado como 'On' en el menú de configuración de la BIOS. Este problema solo afecta a los sistemas donde Secure Boot está configurado en Modo Usuario."}], "metrics": {"cvssMetricV40": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "4.0", "vectorString": "CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "baseScore": 7.0, "baseSeverity": "HIGH", "attackVector": "LOCAL", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "HIGH", "userInteraction": "PASSIVE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "NONE", "subIntegrityImpact": "NONE", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "confidentialityRequirement": "NOT_DEFINED", "integrityRequirement": "NOT_DEFINED", "availabilityRequirement": "NOT_DEFINED", "modifiedAttackVector": "NOT_DEFINED", "modifiedAttackComplexity": "NOT_DEFINED", "modifiedAttackRequirements": "NOT_DEFINED", "modifiedPrivilegesRequired": "NOT_DEFINED", "modifiedUserInteraction": "NOT_DEFINED", "modifiedVulnConfidentialityImpact": "NOT_DEFINED", "modifiedVulnIntegrityImpact": "NOT_DEFINED", "modifiedVulnAvailabilityImpact": "NOT_DEFINED", "modifiedSubConfidentialityImpact": "NOT_DEFINED", "modifiedSubIntegrityImpact": "NOT_DEFINED", "modifiedSubAvailabilityImpact": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED"}}], "cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:H", "baseScore": 6.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "HIGH", "userInteraction": "REQUIRED", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "availabilityImpact": "HIGH"}, "exploitabilityScore": 0.6, "impactScore": 5.9}]}, "weaknesses": [{"source": "[email protected]", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-252"}]}], "references": [{"url": "https://support.lenovo.com/us/en/product_security/LEN-210688", "source": "[email protected]"}]}}